Ignition plug



Dec. 14, Y1948. wu PE IGNITION: PLUG Filed Deo. 27, 1946 INVENTOR Wu f BY mo' EYs Patented Dec. 14, 1948 IGNITION PLUG Wu Pe, Nanking, China Application This invention relates to ignition devices for internal combustion engines and particularly to the so-called glown plug type of ignition device.

An object of this invention is to provide an ignition device of this type constructed and arranged to produce proper timing of the fuel tiring operation in an associated engine.

A further object is to provider an ignition plug of the "glow type so constructed and` arranged that it can be substituted for the conventional high tension spark plug in a conventional internal combustion engine.

A still further object is to provide an ignition plug cf this type capable of properly timing the fuel ignition of an internal combustion. engine without requiring high tension ignition systems, induction coils, distributors or associated parts. These and other objects, which will be apparent, are accomplished by the invention hereinafter described, and which is illustrated in the accompanying drawings in which:

Fig. 1 is a transverse sectional view through an ignition device constructed in accordance with one embodiment of this invention;

Fig. 2 is a similar view of an ignition plug embodying the present invention and adapted to lbe substituted for the conventional high tension spark plug employed in many internal combustion engines;

Fig. 3 is a sectional view of a hot tube type of ignition plug, constructed in accordance with one embodiment of the present invention, and

Fig. 4 is a diagrammatic view illustrating an ignition system employing an ignition plug of the type illustrated in Fig. 2.

In general, the present invention comprises an ignition device having an ignition chamber, which, communicates directly with the associated engine cylinder and a firing chamberin communication with the ignition chamber. In order to control the timing of the ignition operation, a timing grid, in the form of a perforated partition, is interposed between and separates the ring and ignition chambers. The operation of this grid and the manner in which it controls the time of firing in the associated cylinder will be described hereinafter.

In Fig. l, one embodiment of the invention is incorporated in a precombustion ignition device i I formed as a part of the cylinder wall I2. The device is formed with an ignition chamber I3 communicating through a somewhat restricted passage or nozzle I4 with the associated cylinder I5. The device is so formed as to provide a iiring chamber I5 in which a, heating element such as December 27, 194s, serial No. 'nasen In China November 20, 1944 s claims. (ci. 12s- 143) an electrically heated resistance wire I6 is grounded at one end on the wall of the chamber and at the other end is connected to a source of current through a connector I1. Preferably, an auxiliary heating element such forexample as a screen I8 is supported in the iiring chamber around the heating wire I6.

A timing grid is formed in the ignition device and separates the ignition and firing chambers. As illustrated, this grid is in the form of a perforated partition I9 having a plurality of openy ings 2li, the total area of which is accurately formed.

In Fig. 2, the invention is shown applied to an ignition plug adaptedfor use in place of the conventional spark plug employed in high tension ignition systems. In this embodiment, the ignition chamber 2| is formed in a member 22 having a threaded neck 23 for mounting in the threaded spark Aplug opening of the engine. The ring chamber 24 is formed in an intermediate member 25, which is threaded to the upper open end of the base member 22. The outer wall of the intermediate member 25 is shaped to provide a timing grid in the form of a' partition 26 separating the ignition and firing chambers and having orifices 21 similar to orifices 20 in Fig. 1. The vupper open end of the intermediate firing chamber member 25 is closed by a plug or the' like 28, which is threaded to the intermediate member 25 and removable therefrom. -A resistance wire 29 is grounded at one end on the plug 28 and at the other end is adapted to be connected to a low voltage source of current through'a conventional spark plug type connector 30. A heat retaining member 32 in the form of a screen surrounding heating element 29 is also supported by plug 23. When the plug 28 is secured in position it serves to close the firing chamber 24. Obviously, new heating elements can be provided when required merely by providl ing a new closure member 28.

In Fig. 3, the invention is applied to a hot tube type of ignition plug, which can also be substituted for a high tension spark plug in an internal combustion engine. In this embodiment the ignition chamber 33 is formed in a member 34 similar to mem-ber 22 and, like it, adapted for threaded engagement in the conventional spark plug opening of an internal combustion engine. The ring chamber 35 is formed in an elongated tube 36 of suitable heat transmitting material, which is threaded into` an intermediate member 31, which is in turn threaded into the open end of the ignition chamber member 34, the intermediate member being formed with a timing grid in the form of a partition 38 having perforations 39 similar to the perforations in the other embodiment. A heat retaining member 40 is located in the firing chamber 35 and may be supported in any manner, as, for example, on the timing grid Each timing grid is so formed that the velocity of flow of fresh fuel mixture, under the impulse of the compression stroke of the associated piston, from the ignition chamber I3 through the perforations 20 into the firing chamber I5, is greater than the velocity of flame propagation of the fuel mixtures in the ring chamber, until the associated piston reaches a determinate point near the top of its compression stroke, at which time the velocity of mixture flow is reduced to a point below the velocity of flame propagation, with the result that the flame passes from the inner firing chamber into the ignition chamber through the perforated plate. In the ignition chamber the burning of the fuel is practically instantaneous and a high explosive pressure develops which sprays an intense flame into theL cylinder to ignite the mixture therein. The timing grid is so designed that UoFo=UF where Fo is the total of the cross sectional area of the perforated holes in the timing grid F is the cross `sectional area of the nozzle Uo is the coefficient of resistance to flow through i the perforations, and

U is the coeiiicient of resistance to ow through the nozzle.

In operation, when the cylinder is full of fresh unburned fuel mixture at the bottom of the suction stroke,there is still exhaust gas from the previous explosion remaining inside the firing and ignition chambers of the ignition device.`

gether, but act somewhat as if a membrane sep.

arated them. As the pressure increases further, the inert gases are all forced into the firing chamber and are immediately followed by the fresh fuel mixture. At this time the fresh fuel gases entering into Ithe firing chamber are ignited therein, for example, by the electric resistance element I6, which has been raised to a red heat by any suitable low voltage current. At this point, however, the piston is traveling upwardly at high speed and the resulting velocity of flow of the fuel mixture through the perforations in the timing grid into the inner firing chamber is greater than the velocity of flame propagation within the mix.. ture. As a result, burning ofthe mixture is conlined to the firing chamber andcontinuous to be Y so confined as long as these comparative velocities remain. However, as the piston approaches thev the velocity of fuel mixture entering the firing chamber through the timing grid, and to the rate of burning of the gases. Quality of the mixture, the ratio of orifice opening, volume of the chambers, the ratio of the volume of the chambers to each other, and the compression ratio are all closely related to the ignition timing. The velocity of flame propagation varies appreciably with variations in the air fuel ratio, but only slightly with variations in the kinds of fuels used. If the engine runs at constant load and constant speed, the air fuel ratio is usually constant and the ignition device can be easily designed to give an accurate ignition timing. If the load is variable, speed is increased as the load becomes heavier so that velocity of flow through the perforations increases, while increased richness in the fuel mixture results in corresponding increases in the velocity of flame propagation, with the result that ignition timing is automatically adjusted in accordance with variations in speed and load.

In both Figs. 1 and 2, an electrically heated resistance wire is employed to ignite the fuel mixture in the ring chamber in starting. After the engine is running the heat retaining' elements 0r screens I8 and 32 become highly heated and serve as fuel mixture igniting elements, allowing the electric y,current to be shut of! from the resistance element. l

In employing the form shown in Fig. 3, a cold motor is started by first raising the tube 3Bto red heat by applying a gas ame or the like thereto, as is well known in the art. In this modification the heating element 4I) becomes heated as a result of engine operation and thereafter serves as the fuel igniting element.

It will be apparent that the present invention provides an ignition device of the preignition chamber type in which timing of the cylinder explosion can be accurately controlled and that variations in timing are automatically obtained as the result of variations in engine operation resulting from changes in load and speed. The invention can be embodied in an ignition plug, which can be employed in place of conventional high tension plugs and will serve to eliminate the complications of the conventional high tension ignition circuits. As shown in Fig. 4, a simple low voltage line can Ibe connected to the different plugs in the motor cylinder engine. After starting, the current can be entirely shut oft and ignition will result from the heat produced in the associated heating elements by engine operation.

Although certain specific embodiments of the invention have been described in detail, it will be apparent thatvthe invention can be variously modified and adapted within the scope of the appended claims.

I claim:

1. An ignition plug for use in an internal combustion engine having a piston and cylinder, comprising a member adapted to be secured in the wall of said cylinder forming an ignition chamber adapted to communicate with the interior of said cylinder, means associated with said member to form an inner firing chamber and a timing grid separating said chambers and having open,

ings therethrough of such cross sectional area that the velocity of flow of fuel mixture through said grid into said firing chamber under the compression impulse of said piston exceeds the velocity of flame propagation in said firing chamber until the piston travel has reached a determinate point, and a removable closure forsaid firing yafiaoso V chamber having an electrical resistance element supported thereon and extending into said ring chamber for igniting the fuel mixture therein.

2. An ignition plug for use in an internal combustion engine having a piston and cylinder, comprising a member adapted to be secured in the wall of said cylinder forming an ignition chamber adapted to communicate with the interior of said cylinder, means associated with said member to form an inner ring chamber and a timing grid separating said chambers and having openings therethrough of such cross sectional varea that the velocity of flow of fuel mixture through said grid into said ring chamber under the compression impulse of said piston exceeds the velocity of ame propagation in said firing chamber until the piston travel has reached a determinate point, and a closure for said firing chamber having an electrical resistance element supported thereon and extending into said ring chamber for igniting the fuel mixture therein.

3. An ignition plug for use with an internal combustion engine having a piston and cylinder, of means forming an ignition chamber adapted tocommunicate with said cylinder, a hollow tubular member adapted to be heated to fuel igniting temperature forming a firing chamber communicating with said ignition chamber, a timing grid separating said chambers and having openings therethrough of suchcross sectional area that the velocity of flow of fuel mixture into said ilring chamber under compression impulse of said piston exceeds the velocity of flame propagation of the fuel mixtures therein until the piston travel has reached a determinate point, and a heat retaining element located in said firing chamber. y

4. An ignition device for internal combustion engines having a cylinder and piston, comprising a member forming a nring chamber, a fuel ignitengines having a cylinder and piston, comprising a member forming a firing chamber, a fuel igniting element therein, means forming a pressureincreasing ignition chamber between said firing chamber and said cylinder and communicating with said cylinder through a nozzle opening of predetermined diameter, a timing grid between said firing and ignition chambers having openings therethrough, the product of the cross-sectional area of said grid openings and the coefcient of resistance of flow therethrough being substantially equal to the product :of the crossing element therein, means forming a pressureincreasing ignition chamber between said firing chamber and said cylinder and communicating with said cylinder through a nozzle opening of predetermined diameter, a timing gridy between said firing and ignition chambers having openings therethrough, whereby the passage of name at a predetermined time through said grid from said firing to said ignition chamber ignites fuel in vsaid ignition chamber and develops therein a relatively high explosive pressure to project an intense flame into said cylinder.

5. An ignition device for internal combustion sectional area of said nozzle opening and the coeilicient of resistance of ow therethrough, whereby the passage of flame at a predetermined time through said grid from vsaid firing to said ignition chamber ignites fuel in said ignition chamber and develops therein a relatively high explosive pressure to project an intense name into said cylinder.

6. An ignition device for internal combustion engines having a cylinder and piston, comprising a member forming a ring chamber, a fuel igniting element therein, a perforated timinggrid forming one wall of said firing chamber, means forming a pressure-increasing ignition chamber between said firing chamber and said cylinder and communicating with said firing chamber through said grid and with said cylinder through a nozzle opening, whereby the passage of ame at a predetermined time through said grid from said ring chamber ignites the fuel in said ignition chamber so as to develop therein a relatively high explosive4 pressurel and project an intense flame linto said cylinder through said nozzle opening.

WU PE.

REFERENCES 'CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

